\documentclass{article}

\usepackage{multirow}

\begin{document}
\begin{tabular}{| l | l | c | c |}
  \hline 
  \multicolumn{2}{|l|}{Header1}    & Header2 & Header3  \\
  \hline
  \multicolumn{2}{|l|}{text11}      & text12 & text13   \\
  \hline
  \multicolumn{2}{|l|}{text21}     & text22 & text23   \\
  \hline
  \multirow{2}*{text31}      & t311 &text312 & text313  \\
       & t312 & text322 & text323 \\
  \hline 
\end{tabular}
\end{document}
